function loadImg(src) {
    return new Promise(
      (resolve, reject) => {
        const img = document.createElement('img')
        img.onload = () => {
          resolve(img)
        }
        img.onerror = () => {
          const err = new Error(`图片加载失败 ${src}`)
          reject(err)
        }
        img.src = src
      }
    )
  }

  // 测试

const url = 'https://s.poetries.work/uploads/2022/07/ee7310c4f45b9bd6.png'
loadImg(url).then(img => {
  console.log(img.width)
  return img
}).then(img => {
  console.log(img.height)
}).catch(ex => console.error(ex))

const url1 = 'https://s.poetries.work/uploads/2022/07/ee7310c4f45b9bd6.png'
const url2 = 'https://s.poetries.work/images/20210414100319.png'

loadImg(url1).then(img1 => {
  console.log(img1.width)
  return img1 // 普通对象
}).then(img1 => {
  console.log(img1.height)
  return loadImg(url2) // promise 实例
}).then(img2 => {
  console.log(img2.width)
  return img2
}).then(img2 => {
  console.log(img2.height)
}).catch(ex => console.error(ex))